Grub Customizer. Just don’t change it too much (names of menu entries for example) cuz most package managers won’t recognize that that menu entry is actually a menu entry for it’s own install and won’t replace it with a new one when doing a kernel update. So, basically, one of two things will happen. You will either be left with 2 menu entries (one for the new kernel and one for the old one, with the old one being the default) or two, you’ll still be booting the old kernel, even though you have the new one installed (no changes to grub whatsoever). Just rearanging the menu entries is fine though, most package managers won’t mangle that and will recognize the menu entry as part of the OS they’re updating and replace that one with a new one.